lua/ljumptab.h, branch v5.5.1

Global initialization checks name conflict

2025-11-08T14:43:42+00:00

Initialization "global a = 10" raises an error if global 'a' is already defined, that is, it has a non-nil value.

Optimization for vararg tables

2025-09-24T21:33:08+00:00

A vararg table can be virtual. If the vararg table is used only as a base in indexing expressions, the code does not need to create an actual table for it. Instead, it compiles the indexing expressions into direct accesses to the internal vararg data.

Keep the order left-right in shifts

2025-08-20T17:31:07+00:00

Opcodes OP_SHLI-OP_SHRI and the cases for opcodes OP_SHL-OP_SHR were out of order.

Several details about 5.4.0 rc1

2020-04-23T17:48:15+00:00

Corrected several small details: added 'const', adjusts in tabs x spaces, removed unused #includes and #defines, misspellings, etc.

OP_LOADFALSE broken in two instructions

2020-02-11T14:12:33+00:00

Changed internal representation of booleans

2020-01-06T14:38:31+00:00

Instead of an explicit value (field 'b'), true and false use different tag variants. This avoids reading an extra field and results in more direct code. (Most code that uses booleans needs to distinguish between true and false anyway.)

Removed arithmetic opcodes with immediate operand

2019-09-10T16:20:03+00:00

The difference in performance between immediate operands and K operands does not seem to justify all those extra opcodes. We only keep OP_ADDI, due to its ubiquity and because the difference is a little more relevant. (Later, OP_SUBI will be implemented by OP_ADDI, negating the constant.)

First version of OP_MMBIN opcodes

2019-08-27T16:59:39+00:00

In arithmetic/bitwise operators, the call to metamethods is made in a separate opcode following the main one. (The main opcode skips this next one when the operation succeeds.) This change reduces slightly the size of the binary and the complexity of the arithmetic/bitwise opcodes. It also simplfies the treatment of errors and yeld/resume in these operations, as there are much fewer cases to consider. (Only OP_MMBIN/OP_MMBINI/OP_MMBINK, instead of all variants of all arithmetic/bitwise operators.)

Keep correct type for immediate operands in comparisons

2019-03-22T16:37:17+00:00

When calling metamethods for things like 'a < 3.0', which generates the opcode OP_LTI, the C register tells that the operand was converted to an integer, so that it can be corrected to float when calling a metamethod. This commit also includes some other stuff: - file 'onelua.c' added to the project - opcode OP_PREPVARARG renamed to OP_VARARGPREP - comparison opcodes rewritten through macros

New semantics for the integer 'for' loop

2019-03-19T13:53:18+00:00

The numerical 'for' loop over integers now uses a precomputed counter to control its number of iteractions. This change eliminates several weird cases caused by overflows (wrap-around) in the control variable. (It also ensures that every integer loop halts.) Also, the special opcodes for the usual case of step==1 were removed. (The new code is already somewhat complex for the usual case, but efficient.)